There are people who use the excuse that they are working at overcoming offense. But that's not what the Bible instructs us to do. James 1:23-25 clearly states that only the doers of the Word will be blessed.
For if anyone is a hearer of the word and not a doer, he is like a man observing his natural face in a mirror; for he observes himself, goes away, and immediately forgets what kind of man he was. But he who looks into the perfect law of liberty and continues in it, and is not a forgetful hearer but a doer of the work, this one will be blessed in what he does.
A doer of the Word is not someone who merely listens to what the Word says, but rather applies what he has heard to his life. How do you suppose it would sound if someone said, "I am working at not lying"? No, if you simply tell the truth, you won't lie! It's not those who are working at not lying who are blessed, but those who speak the truth.
God doesn't accept the idea of "working on it" any more than you would if your spouse said he or she was "working on" being married. Your spouse would get the slack jerked out of him or her very quickly!
When someone states that they are "working on it," what they are actually revealing is that they are not yet willing to obey God. Isn't that right? It's a whole lot easier to justify yourself by saying that you are working on something than it is to implement the Word of God or to admit you're in sin. Many times you can con people with such statements, but you can't con God because He looks upon the heart.
There is not one sin that the blood of Jesus cannot eradicate. His blood is all-powerful. And as a result, there is no excuse for a Christian to be offended. No one—no matter how heartbreaking, horrific, or desperate the situation—can develop an excuse for being offended that is acceptable to God.
You may have convinced yourself that your basis for offense is a worthy one, but you will never persuade God. He gave His Son to die so that all of humanity could be forgiven of their shortcomings. If you have accepted God's forgiveness, then you must be willing to give it to others. "For if you forgive men their trespasses, your heavenly Father will also forgive you." (Matthew 6:14)
There is no permissible excuse for disobeying God. When you stand before Him, and He asks, "Why didn't you obey My Word?" you cannot come up with an excuse that will satisfy God. You may offer an excuse, but He will reply, "I empowered you with supernatural ability to do all that was written in My Word. All you had to do was make the decision to obey." And the bottom line will be that you simply made poor choices.
In the same manner, there is no acceptable excuse for harboring unforgiveness because of an offense. Although someone always tries to defend their reason for being offended by saying, "But you don't know what they did to me, or how many years I have had to put up with it." However, the Lord didn't exclude anyone when He said, "Whenever you stand praying, if you have anything against anyone, forgive him, that your Father in heaven may also forgive you your trespasses." (Mark 11:25) So, apparently it doesn't matter what the offense was, you are still required to forgive.